Approximately 8.5 percent of people with psoriasis develop psoriatic arthritis, a condition characterized by psoriasis with inflammation of the joints and of the tissues around the joints. People with psoriasis are also commonly diagnosed with depression, which in turn is also associated with increased systemic inflammation.
The researchers hypothesized that people with psoriasis who developed depression were also at a higher risk of developing psoriatic arthritis.
“For many years, the rheumatology and dermatology communities have been trying to understand which patients with psoriasis go on to develop psoriatic arthritis and how we might detect it earlier in the disease course,” Cheryl Barnabe, MD, MSc, senior investigator of the study and a researcher at the University of Calgary, said in a press release.
Using a patient records database in the United Kingdom, the research team identified over 70,000 people with a diagnosis of psoriasis. Through follow-up records, the team then identified people who were later diagnosed with depression and those who then developed psoriatic arthritis.
Based on statistics, psoriasis patients who were diagnosed with depression were at a 37 percent higher risk of developing psoriatic arthritis compared to psoriasis patients who did not develop depression.
“There is a tendency to think of depression as a purely ‘psychological’ or ’emotional’ issue, but it also has physical effects, and changes in inflammatory and immune markers have been reported in depressed people,” said Scott Patten, MD, PhD, of the Cumming School of Medicine in Calgary. “Depression may be a risk factor for a variety of chronic conditions, and this research is an example of how big data approaches can identify these associations.”
The study also highlights the need for physicians to help psoriasis patients identify and treat depression. Treating depression in psoriasis patients can be achieved through effective care of psoriasis plus psychosocial management to help ease the cosmetic burden of the disease, according to the study’s authors.
“It is evident to physicians who treat patients with psoriasis that there is a significant psychological and social burden associated with this disease, which is reflected in an increase in the rates of depression,” said Laurie Parsons, MD, also of the Cumming School of Medicine.
“This study brings us a little closer to understanding the role of chronic inflammation as a systemic player in both the physical and psychological manifestations of psoriasis and underscores the need for closer attention to symptoms of depression in this group of patients,” Parsons added.
The study also questions the biological mechanisms that cause depression to increase the risk for psoriatic arthritis: It could be due to the increased systemic inflammation or due to the alteration of lifestyle, including physical activity or the ability of maintaining a healthy diet, which tends to be greatly affected by depression.
“This study raises important questions on the role of systemic inflammation, which is also elevated in depression, in driving a disease phenotype, which needs to be confirmed in clinical cohorts,” Barnabe said.